Breathing Pure Oxygen Research Articles

Effects of oxygen-prebreathing on tissue nitrogenation in normobaric and hyperbaric conditions.

Breathing pure oxygen causes nitrogen washout from tissues, a method commonly deployed to prevent decompression sickness from hypobaric exposure. Theoretically prebreathing oxygen increases the capacity for nitrogen uptake and potentially limits supersaturation during dives of short duration. We aimed to use 13N2, a radioactive nitrogen isotope, to quantify tissue nitrogen following normobaric and hyperbaric exposures. Twenty Sprague Dawley rats were divided in 4 conditions; normobaric prebreathe, normobaric control, hyperbaric prebreathe, hyperbaric control. Prebreathed rats breathed oxygen for 1 h prior to the experiment whilst controls breathed air. Normobaric rats breathed air containing 13N2 at 100 kPa for 30 min, whereas hyperbaric rats breathed 13N2 at 700 kPa before being decompressed and sedated using air-isoflurane (without 13N2 for a few minutes). After euthanization, blood, brain, liver, femur and thigh muscle were analyzed by gamma counting. At normobaria prebreathing oxygen resulted in higher absolute nitrogen counts in blood (p = .034), as well as higher normalized counts in both the liver and muscle (p = .034). However, following hyperbaric exposure no differences were observed between conditions for any organ (p>.344). Both bone and muscle showed higher normalized counts after hyperbaria compared to normobaria. Oxygen prebreathing caused nitrogen elimination in normobaria that led to a larger "sink" and uptake of 13N2. The lack of difference between conditions in hyperbaria could be due to the duration and depth of the dive mitigating the effect of prebreathing. In the hyperbaric conditions the lower counts were likely due to off-gassing of nitrogen during the sedation procedure, suggest a few minutes was enough to off-gas in rodents. The higher normalized counts under hyperbaria in bone and muscle likely relate to these tissues being slower to on and off-gas nitrogen. Future experiments could include shorter dives and euthanization while breathing 13N2 to prevent off-gassing.

Kidney stone twinkling power in elevated oxygen, carbon dioxide, and nitrogen environments

Clinically, ∼66% of kidney stones exhibit the Doppler ultrasound twinkling artifact. Previous studies show breathing pure oxygen at elevated pressures increases twinkling compared to ambient air. Here, we investigate how different gases influence twinkling on ex vivo and in vivo human kidney stones. 38 kidney stones were imaged with a research ultrasound system and ATL L7-4 transducer in elevated oxygen, carbon dioxide, and nitrogen environments. In vivo stones were imaged with the same ultrasound system and ATL C5-2 transducer in 25 human subjects before and after breathing pure oxygen for 15 min. IQ data were processed by calculating the average Doppler power, or twinkling, for a region of interest containing the stone. In the lab, increasing oxygen by 55%, carbon dioxide by 100%, and nitrogen by 17% increased twinkling power an average of 70 ± 28%, 137 ± 53%, and 79 ± 31%, respectively. In human subjects, breathing oxygen increased twinkling power an average of 27 ± 58%, with seven subjects showing a strong increase (>30%); stone composition and patient age influenced twinkling in patients breathing oxygen. These results suggest that varying ambient gases may be leveraged to increase the consistency of twinkling and improve kidney stone detection with ultrasound. [Work supported by the PSU Center for Biodevices.]

Effect of Anesthetic Carrier Gas on In Vivo Circulation Times of Intravenously Administered Phospholipid Oxygen Microbubbles in Rats.

For the treatment of tumor hypoxia, microbubbles comprising oxygen as a majority component of the gas core with a stabilizing shell may be used to deliver and release oxygen locally at the tumor site through ultrasound destruction. Previous work has revealed differences in circulation half-life in vivo for perfluorocarbon-filled microbubbles, typically used as ultrasound imaging contrast agents, as a function of anesthetic carrier gas. These differences in circulation time in vivo were likely due to gas diffusion as a function of anesthetic carrier gas, among other variables. This work has motivated studies to evaluate the effect of anesthetic carrier gas on oxygen microbubble circulation dynamics. Circulation time for oxygen microbubbles was derived from ultrasound image intensity obtained during longitudinal kidney imaging. Studies were constructed for rats anesthetized on inhaled isoflurane with either pure oxygen or medical air as the anesthetic carrier gas. Results indicated that oxygen microbubbles were highly visible via contrast-specific imaging. Marked signal enhancement and duration differences were observed between animals breathing air and oxygen. Perhaps counterintuitively, oxygen microbubbles disappeared from circulation significantly faster when the animals were breathing pure oxygen compared with medical air. This may be explained by nitrogen counterdiffusion from blood into the bubble, effectively changing the gas composition of the core, as has been observed in perfluorocarbon core microbubbles. Our findings suggest that the apparent longevity and persistence of oxygen microbubbles in circulation may not be reflective of oxygen delivery when the animal is anesthetized breathing air.

Proton FLASH effects on mouse skin at different oxygen tensions

Objective. Irradiation at FLASH dose rates (>40 Gy s−1) has received great attention due to its reported normal tissue sparing effect. The FLASH effect was originally observed in electron irradiations but has since been shown to also occur with both photon and proton beams. Several mechanisms have been proposed to explain the tissue sparing at high dose rates, including effects involving oxygen, such as depletion of oxygen within the irradiated cells. In this study, we investigated the protective role of FLASH proton irradiation on the skin when varying the oxygen concentration. Approach. Our double scattering proton system provided a 1.2 × 1.6 cm2 elliptical field at a dose rate of ∼130 Gy s−1. The conventional dose rate was ∼0.4 Gy s−1. The legs of the FVB/N mice were marked with two tattooed dots and fixed in a holder for exposure. To alter the skin oxygen concentration, the mice were breathing pure oxygen or had their legs tied to restrict blood flow. The distance between the two dots was measured to analyze skin contraction over time. Main results. FLASH irradiation mitigated skin contraction by 15% compared to conventional dose rate irradiation. The epidermis thickness and collagen deposition at 75 d following 25 to 30 Gy exposure suggested a long-term protective function in the skin from FLASH irradiation. Providing the mice with oxygen or reducing the skin oxygen concentration removed the dose-rate-dependent difference in response. Significance. FLASH proton irradiation decreased skin contraction, epidermis thickness and collagen deposition compared to standard dose rate irradiations. The observed oxygen-dependence of the FLASH effect is consistent with, but not conclusive of, fast oxygen depletion during the exposure.

Addition of hyperbaric oxygen therapy versus usual care alone for inflammatory bowel disease: A systematic review and meta-analysis

ObjectiveInflammatory bowel disease (IBD) is a chronic idiopathic inflammatory disease that includes ulcerative colitis (UC) and Crohn's disease (CD). Hyperbaric oxygen therapy (HBOT) involves breathing pure oxygen in a pressurized environment. Existing literature suggests that HBOT may be an effective therapy for IBD, but a quantitative analysis is lacking. This study aims to estimate the adjunctive role of HBOT in treating IBD and lowering its recurrence rate. DesignSystematic review and meta-analysis. MethodsThe Cochrane Library, EMBASE, PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and Wanfang databases were systematically searched by two reviewers independently. Meta-analyses were performed using Review Manager (RevMan, version 5.3). A random-effects model was applied due to the heterogeneity between studies. ResultsTwenty-nine out of the initially identified 606 articles were covered in this review, with a total of 2151 patients (2071 for UC and 80 for CD). No randomized data of HBOT for CD were included. Among UC patients, usual care plus HBOT were more likely to achieve a clinical response than usual care alone (risk ratio [RR], 1.24; 95% confidence interval (CI), 1.17 to 1.31; P < 0.001). Subgroup analysis showed that the number of HBOT sessions had no statistically significant effect on overall efficacy (P > 0.05). The pooled data showed a lower recurrence rate in the usual care plus HBOT group (RR, 0.35; 95% CI, 0.24 to 0.53; P < 0.001). The standardized mean difference in the serum tumor necrosis factor level between HBOT and non-HBOT groups was -2.13 (95% CI, -3.09 to -1.18; P < 0.001). No severe adverse events of HBOT were observed. ConclusionsHBOT might be an effective and safe adjunctive treatment for IBD. Further studies are required to investigate the optimal protocol of HBOT in IBD treatment.

Current Status of Hyperbaric Oxygen Therapy and Its Application

Hyperbaric oxygen therapy is a method of breathing pure oxygen or high-concentration oxygen in a highpressure environment to treat hypoxic diseases and related diseases. According to clinical verification, this therapy has an irreplaceable effect on certain diseases and has gradually become a comprehensive clinical treatment. One of the main methods of certain diseases is widely recognized by the medical field at home and abroad. The development history, treatment principles, key technologies, and future development trends of hyperbaric oxygen are discussed in detail, provide a research direction for the development of hyperbaric oxygen therapy in the future, and at the same time, it has also improved physicians' awareness of hyperbaric oxygen therapy, so as to improving Industry influence.

Could hyperbaric oxygen be an effective therapy option for pathological scars? A systematic review and meta-analysis

Background Hyperbaric oxygen (HBO) therapy involves breathing pure oxygen or a high oxygen concentration above atmospheric (ATM) pressure in an enclosed chamber. Studies on pathological scars have demonstrated that HBO can inhibit the formation of pathological scars. Objective To evaluate the efficacy of HBO in the treatment of pathological scars via meta-analysis. Methods Searches were run on various databases, including the Cochrane, Embase, PubMed, Web of Science, and CNKI databases. A comparative study was conducted on patients with pathological scars treated with or without HBO. We used RevMan 5.4 software to determine the recurrence rate, treatment satisfaction, and Vancouver Scar Scale(VSS) score in the pathological scar. Results A total of 543 publications were identified; after screening, four were selected for review, including one randomized controlled trial (RCT), one controlled clinical trial (CCT), and two retrospective cohort studies. Meta-analysis results showed that HBO treatment reduced the pathological scar recurrence rate after surgery and radiotherapy (OR = 0.26, 95% CI: 0.13–0.52, p = 0.0001). Patients had higher satisfaction after HBO therapy (OR = 4.45, 95% CI: 1.49–13.30, p = 0.007). The Vancouver scar scale (VSS) score of patients with pathological scars was significantly improved in the HBO group (SMD: −3.82, 95% CI: −6.07to −0.49, p = 0.02). Conclusions HBO treatment decreased the recurrence rate of pathological scars after surgery and radiotherapy, increased patient satisfaction, and reduced the VSS score, thus providing a new way to treat pathological scar hyperplasia. However, evaluation of the longer-term effects of HBO treatment requires further comprehensive studies, including more RCTs.

ПРИМЕНЕНИЕ ГИПЕРБАРИЧЕСКОЙ ОКСИГЕНАЦИИ В ЛЕЧЕНИИ ТЕРАПЕВТИЧЕСКОЙ ПАТОЛОГИИ

Hyperbaric oxygenation (HBO) is a method based on breathing pure oxygen under high pressure, which makes it possible to eliminate any forms of oxygen debt by delivering oxygen to organs and tissues by dissolving it in the body’s liquid media. The list of indications for HBO is constantly expanding, and a number of studies prove the effectiveness of its use in the treatment of various kinds of therapeutic pathologies. Within the framework of this article, the author analyzes the features of the use of HBO in the treatment of a number of diseases.

Standard cochlear implants as electrochemical sensors: Intracochlear oxygen measurements in vivo

Cochlear implants are the most successful neural prostheses worldwide and routinely restore sensorineural hearing loss by direct electrical stimulation of the auditory nerve. Enhancing this standard implant by chemical sensor functionality opens up new possibilities, ranging from access to the biochemical microenvironment of the implanted electrode array to the long-term study of the electrode status. We developed an electrochemical method to turn the platinum stimulation microelectrodes of cochlear implants into electrochemical sensors. The electrodes showed excellent and stable chemical sensor properties, as demonstrated by in vitro characterizations with combined amperometric and active potentiometric dissolved oxygen and hydrogen peroxide measurements. Linear, stable and highly reproducible sensor responses within the relevant concentration ranges with negligible offset were shown. This approach was successfully applied in vivo in an animal model. Intracochlear oxygen dynamics in rats upon breathing pure oxygen were reproducibly and precisely measured in real-time from the perilymph. At the same time, correct implant placement and its functionality was verified by measurements of electrically evoked auditory brainstem responses with clearly distinguishable peaks. Acute measurements indicated no adverse influence of electrical stimulation on electrochemical measurements and vice versa. Our work is ground-breaking towards advanced implant functionality, future implant lifetime monitoring, and implant-life-long in situ investigation of electrode degradation in cochlear implant patients.

Breath holding as an example of extreme hypoventilation: experimental testing of a new model describing alveolar gas pathways.

What is the central question of this study? We modelled the alveolar pathway during breath holding on the hypothesis that it follows a hypoventilation loop on the O2 -CO2 diagram. What is the main finding and its importance? Validation of the model was possible within the range of alveolar gas compositions compatible with consciousness. Within this range, the experimental data were compatible with the proposed model. The model and its characteristics might allow predictions of alveolar gas composition whenever the alveolar ventilation goes to zero; for example, static and dynamic breath holding at the surface or during ventilation/intubation failure in anaesthesia. According to the hypothesis that alveolar partial pressures of O2 and CO2 during breath holding (BH) should vary following a hypoventilation loop, we modelled the alveolar gas pathways during BH on the O2 -CO2 diagram and tested it experimentally during ambient air and pure oxygen breathing. In air, the model was constructed using the inspired and alveolar partial pressures of O2 ( and , respectively) and CO2 ( and , respectively) and the steady-state values of the pre-BH respiratory exchange ratio (RER). In pure oxygen, the model respected the constraint of . To test this, 12 subjects performed several BHs of increasing duration and one maximal BH at rest and during exercise (30W cycling supine), while breathing air or pure oxygen. We measured gas flows, and before and at the end of all BHs. Measured data were fitted through the model. In air, =150±1mmHg and =0.3±0.0mmHg, both at rest and at 30W. Before BH, steady-state RER was 0.83±0.16 at rest and 0.77±0.14 at 30W; =107±7mmHg at rest and 102±8mmHg at 30W; and =36±4mmHg at rest and 38±3mmHg at 30W. By model fitting, we computed the RER during the early phase of BH: 0.10 [95% confidence interval (95% CI) =0.08-0.12] at rest and 0.13 (95% CI=0.11-0.15) at 30W. In oxygen, model fitting provided : 692 (95% CI=688-696) mmHg at rest and 693 (95% CI=689-698) mmHg at 30W. The experimental data are compatible with the proposed model, within its physiological range.

Monitoring of Fast Variations in the Content of Endogenous CO in Exhaled Air by Methods of Diode Laser Spectroscopy

Methods of diode laser spectroscopy were applied for monitoring of fast physiological variations in the content of endogenous carbon monoxide (CO) in exhaled air. To this end, a CO analyzer based on a tunable diode laser emitting radiation around 2.35 μm at room temperature was constructed. CO concentration in exhaled air was determined by measuring resonance absorption of CO molecule at the R(6) line of the 0–2 band in the vicinity of 4285 cm–1. Using this line that is well separated from the nearby absorption lines of Н2О enables high selectivity of CO analysis under the conditions of high humidity of analyzed air. The possibility of monitoring fast physiological variations of CO content in exhaled air of humans and animals by means of the developed system was demonstrated in studies involving a number of physiological load tests, such as breathing pure oxygen (both humans and rats), physical load, and hyperventilation. The dynamics of CO release caused by certain pharmaceutical drugs was also studied. It is demonstrated that laser diagnostics of CO in the spectral region near 2.35 μm allows detecting fast dynamic processes of release of this gas molecule that represents one of the signaling and metabolite molecules in exhaled air when conducting various physiological and medical studies, investigating trends and interrelation of processes responsible for production, transport, buffering, and release of CO in an organism.

Effects of 100 % oxygen during exercise in patients with interstitial lung disease

PurposeHypoxemia limits exercise in some patients with interstitial lung disease (ILD). High levels of supplemental oxygen during exercise might allow physical training at a higher level and more effective pulmonary rehabilitation (PR). Our goals were to use graded cardiopulmonary exercise testing (CPET) to determine whether hyperoxia (FIO2≈1.0) increased exercise tolerance in patients with mild to moderate ILD. MethodsWe studied 6 patients with ILD, including idiopathic pulmonary fibrosis (IPF) and nonspecific interstitial pneumonia (NSIP). The study population included 3 females and 3 males (age 69 ± 5 [SD] years; FVC 61 ± 14 %; absolute DLCO 53 ± 19 %). Subjects underwent 2 ramped (15 W/min) CPET protocols on a cycle ergometer (Jaeger Oxycon Pro™, CareFusion Respiratory Care) breathing either air or oxygen (FIO2≈1.0) from a Douglas bag in random order. ResultsMinute ventilation (VE) increased significantly during CPET breathing air (pre CPET, 18 ± 2 [SEM] L/min; post CPET, 47 ± 6; P = 0.01), but it did not increase significantly breathing oxygen (pre CPET, 15 ± 3 [SEM]; post CPET, 29 ± 9; P = 0.06). Likewise, carbon dioxide production (VCO2) increased significantly during CPET breathing air (pre CPET, 450 ± 93 [SEM] mL/min; post CPET, 1311 ± 200; P = 0.01), but it did not increase significantly breathing oxygen (pre CPET, 369 ± 129; post CPET, 847 ± 832; P = 0.09). Exercise time during CPET did not differ significantly (P = 0.34) in air (5.6 ± 0.9 [SEM] min) or oxygen (7.0 ± 1.8). Increases in heart rate (HR) and Borg dyspnea index (BDI) after CPET were not affected by breathing oxygen. ConclusionExercise-induced increases in VE and VCO2 were prevented by breathing pure oxygen during CPET, demonstrating both decreased ventilatory drive and more efficient exercise at achieved workloads. Hyperoxia could enhance the ability of patients with ILD to train at higher workloads, resulting in more effective rehabilitation.

Мониторинг быстрых вариаций содержания эндогенного СО в выдыхаемом воздухе методами диодной лазерной спектроскопии

A.I.Dyachenko 1, E.V.Stepanov 1, Yu.A.Shulagin 2 1 Prokhorov General Physics Institute of the Russian Academy of Science 2 Institute of Biomedical Problems of the Russian Academy of Science Metods of tunable diode laser spectroscopy were used to monitor fast physiological variations of endogenous carbon monoxide (CO) content in expired air. For these purposes, a CO analyzer was created on the basis of a tunable diode laser emitting in the region of 2.35 μm at room temperature. To determine the concentration of CO in exhaled air, the value of the resonance absorption of this molecule in the R (6) line of the 0–2 band located near 4285 cm – 1 was measured. The use of this line, which is well isolated from nearby H2O absorption lines, allows one to ensure high selectivity of CO analysis in conditions of high humidity of the analyzed air. The capabilities of monitoring rapid physiological variations in the CO content in the exhaled air of humans and animals using the developed system were demonstrated in studies using different physiological stress tests, such as pure oxygen breathing (both in humans and rats), physical activity, and hyperventilation. The dynamics of the allocation of CO due to the use of certain pharmaceuticals were also observed. It was shown that laser analysis of CO in the spectral range of 2.35 μm makes it possible to detect fast dynamic processes of the evolution of this gaseous molecule, which is one of the signal metabolite molecules, during various physiological and medical studies, to study the patterns and relationships of the processes responsible for production, transport, buffering and release of CO in the body.

Repeated exposure to hyperbaric hyperoxia affects mitochondrial functions of the lung fibroblasts.

Hyperbaric oxygen (HBO) therapy, i.e. breathing pure oxygen under increased environmental pressures serves as a treatment for diverse medical conditions. However, elevated oxygen concentration can be detrimental to central nervous system or lungs. Our study aimed to evaluate the effects of repeated exposure to HBO on mitochondrial respiration assessed by high-resolution respirometry (HRR), cell viability estimated by PrestoBlue® reaction, morphology analyzed by routine phase contrast and fluorescent microscopy, and superoxide dismutase (SOD) and citrate synthase (CS) activities using human lung fibroblasts. The cells were exposed to HBO for 2 h per day for 5 consecutive days. One day after the last exposure, HBO cells displayed significantly smaller area and perimeter, compromised viability and elevated SOD activity. No changes were detected in CS activity or quality of mitochondrial network. HRR revealed impaired mitochondrial oxygen consumption manifested by increased leak respiration, decreased activity of complex II and compromised ATP-related oxygen consumption when fatty acids were oxidized. Our findings document that in conditions mimicking chronic intermittent exposure to HBO, lung fibroblasts suffer from compromised mitochondrial respiration linked to complex II and impaired cellular growth in spite of increased antioxidant defense. Underlying mechanism of this HBO-induced mitochondrial dysfunction should be further explored.

Microcirculation in the skin of the upper extremities and the parameters of central hemodynamics with hourly breathing of pure oxygen

The aim of the study was to assessment the effects of normobaric oxygenation (NBO) with 100 % oxygen for 60 minutes on the state of central and peripheral hemodynamics of a humans. Material and methods. The method of laser Doppler flowmetry and capillaroscopy was used in 10 healthy men (27.3±4) initially, at 5-15, 45-55 minutes of the NBU and during the recovery period. Results. Individual differences between the testers, depending on the state of the autonomic nervous system, assessed using the Kerdo index (IR), are revealed. The testers with IR 0 showed a two-phase reaction. Conclusions. The physiological response to hourly breathing with pure oxygen can be different and depends on the state of the tone of the autonomic nervous system.

Treatment Of Hypoxic Tumours With Plasma Jets

A challenge in cancer therapy is the destruction of tumours, where there is the potential issue of cancer cells residing within hypoxic tissue. The concept of hypoxic regions within tumours dates back to 1909 and it has long been suspected that under low oxygen tension, cells are “afforded” radiation protection. It has been shown many decades ago, that raising the concentration of oxygen in tissues can significantly improve the outcomes in radiotherapy. For example, in 1953, a meta-analysis of 83 randomised trials showed a clear benefit from raising tissue oxygen tension during radiation therapy, with the clearest benefits seen in cancers of neck and head [1]. However, there are only a limited number of ways to raise oxygen tension in tissues, which include breathing pure oxygen at or above standard temperature and pressure, or hypoxic modification by the means of an administered drug (e.g. nimorazole) [2, 3, 4]. Recently, we (and other research groups) have shown that cold atmospheric plasma jets not only readily deliver reactive oxygen and nitrogen species (RONS) into tissue, but concomitantly raise the oxygen tension in tissue. Combined RONS and oxygen delivery, may significantly elevate oxidative stress in cancer cells, resulting in destruction of these cells within hypoxic tumours. In this presentation, I will provide a brief historical overview of research on the modification of hypoxia in cancers; I will then discuss results that have shown how plasma jets can be used to treat hypoxia in tumours (through delivery of RONS and oxygen into tissues). I will also discuss the potential opportunities, challenges and limitations of the plasma technology for treatment of hypoxic cancer tumours.

Oxygen Sensing in the Pulmonary Circulation

Since the original description of hypoxic pulmonary vasoconstriction (HPV) by Von Euler and Liljestrand in 1946, where they concluded, “breathing of pure oxygen lowered the pulmonary arterial pressure and oxygen-lack raised it,”1 the precise oxygen-sensing mechanism within the lungs has remained an enigma. Nevertheless, there seems to be some agreement to an overall mechanism for HPV: the primary oxygen sensor is the pulmonary artery smooth muscle cells (PASMC) mitochondrial electron transport chain (ETC); the ETC-produced superoxide/reactive oxygen species (ROS) is the mediator; and redox-sensitive plasma membrane voltage-gated potassium (Kv) channels are the effectors.2 Intriguingly, a similar sensor-mediator-effector model seems to operate in other areas where oxygen is sensed in the body, such as the ductus arteriosus or the carotid body.2 But many controversies exist. Although several groups, including ours, show that acute hypoxia decreases superoxide production from ETC complexes I and III, others find that hypoxia increases superoxide production.2,3 Regardless, most agree that it is the more stable and diffusible hydrogen peroxide (H2O2), produced from superoxide via the mitochondrial MnSOD (manganese superoxide dismutase) that eventually reaches the cell membrane to regulate Kv channels.2,3 However, once again controversy exists. Many groups, including ours, show that decreased levels of H2O2 (a reducing signal) directly inhibits Kv channels (like Kv1.5),2,3 depolarizing the plasma membrane, increasing Ca2+ influx through L-type Ca2+ channels, and causing PASMC contraction2,3 (Kv channels are intrinsically redox sensitive and animals lacking Kv1.5 lack HPV4). Others suggest that increased levels of H2O2 (an oxidative signal) primarily result in an endoplasmic reticulum-mediated calcium release, with K+ channel inhibition as a downstream effect.3 Much has been written about the first controversy, which tends to …

Hyperbaric Oxygen Therapy and Quality of Life: A Systematic Review

Objective: Hyperbaric oxygen therapy (HBOT) involves breathing pure oxygen in a high-pressure chamber. HBOT is a well-established treatment for several diseases, such as serious infections, chronic diabetic foot ulcer, radiation injury, and hidradenitis suppurativa. There are various troublesome diseases that decrease pleasure in life in patients. HBOT has excellent effects in improving QOL in patients with acute and chronic diseases. The present study aimed at assessing the researches that focus on improving the QOL after HBO treatments. Methods: A systematic quest was conducted to evaluate English papers (clinical trials) that were published before April 2017. We searched PubMed, institute of scientific information (ISI), SCOPUS, Web of Science, Ovid, Science direct, ProQuest, Wiley, Cochran, Ebsco host, and Google Scholar. The reference lists of all the articles and electronic journals were searched for further studies. The JAMA users guide evaluation scales for RCTs was used to assess quality of the researched articles. Inclusion and exclusion criteria were extracted according to the scientific criteria. Sample size was 806 patients. Results: Finally, 15 published articles were extracted. Most researches were done in UK (26.7%), Israel (20%), and Sweden (20%). The mean age in HBOT group was 41.88, with a male to female ratio of 1.52. The mean age in the control group was 38.29, with a male to female ratio of 2.14. The most frequent clinical trials were those on the treatment of diabetic foot ulcer (20%), post-concussion syndrome (13.3%), pelvic radiotherapy (13.3%), and chronic arm lymphedema after radiotherapy (13.3%). The most QOL questionnaires used were SF-36 (21.4%), EORTC (European organization for research and treatment of cancer) QLQ-C30, head and neck cancer module (H&N35), and performance status scale (PSS). Conclusions: A significant effect of HBOT on improving QOL in patients’ outcomes and symptoms was found compared with the control group. We found improved QOL in patients with diabetic foot ulcer, post-concussion syndrome, pelvic radiotherapy, post stroke, hidradenitis suppurativa, tonsillar fossa tumor radiotherapy, jaw osteonecrosis, and fibromyalgia syndrome. We suggest that HBOT be added to conventional treatment of these patients as an adjuvant.

T1 relaxation time constants, influence of oxygen, and the oxygen transfer function of the human lung at 1.5 T—A meta-analysis

PurposeTo pool and summarize published data from magnetic resonance longitudinal relaxation measurements of the human lung at 1.5T to provide a reliable basis of T1 relaxation time constants of healthy lung tissue both under respiration of room air and of pure oxygen. In particular, the oxygen-induced shortening of T1 was evaluated. Materials and methodsThe PubMed database was comprehensively searched up to June 2016 for original publications in English containing quantitative T1 data (at least mean values and standard deviations) of the lung parenchyma of healthy subjects (minimum subject number: 3) at 1.5T. From all included publications, T1 values of the lung of healthy subjects were extracted (inhaling room air and, if available, inhaling pure oxygen). Weighted mean values and standard deviations of all extracted data and the oxygen transfer function (OTF) were calculated. Results22 publications were included with a total number of 188 examined healthy subjects. 103 of these subjects (from 13 studies) were examined while breathing pure oxygen and room air; 85 subjects were examined only under room-air conditions. The weighted mean value (weighted sample standard deviation) of the room-air T1 values over all 22 studies was 1196ms (152ms). Based on studies with room-air and oxygen results, the mean T1 value at room-air conditions was 1172ms (161ms); breathing pure oxygen, the mean T1 value was reduced to 1054ms (138 ms). This corresponds to a mean T1 reduction by 118ms (35ms) or 10.0 % (2.3 %) and to a mean OTF value of 1.22 (0.32)×10−3s−1/(%O2). ConclusionThis meta-analysis with data from 188 subjects indicates that the average T1 relaxation time constant of healthy lung tissue at 1.5T is distributed around 1200ms with a standard deviation of about 150 ms; breathing pure oxygen reduces this value significantly by 10 % to about 1050 ms.

Color-Doppler ultrasound imaging of in situ human kidney stones in a hyperbaric chamber

Overpressure has been shown to reduce the color-Doppler ultrasound twinkling artifact on ex vivo human kidney stones, leading to the hypothesis that surface crevice microbubbles cause twinkling. For the first time, we investigate the effect of overpressure on in situ human kidney stones. Thus far, five human subjects with kidney stones known to twinkle have been imaged with a Philips/ATL P4-2 transducer and Verasonics ultrasound system for 45 minutes in a hyperbaric chamber. Subjects breathed ambient air while exposed to a maximum pressure of 4 atmospheres absolute (ATA), except for a scheduled decompression stop at 1.6 ATA where subjects breathed pure oxygen. Twinkling was quantified in terms of Doppler power over 2 min intervals before pressurization (baseline), at 4 ATA, and at 1.6 ATA. Preliminary results (averaged over 3 of the 5 subjects) indicate no change in twinkling at 4 ATA compared to baseline levels (ratio of Doppler powers = 1.09±0.27). Twinkling almost doubled, though, during the pure oxygen stage at 1.6 ATA compared to baseline levels (ratio of Doppler powers = 1.85±0.58). The increase in twinkling associated with breathing pure oxygen continues to support the crevice microbubble hypothesis. Higher pressures than explored in this study may be needed to reduce twinkling on in situ stones, as was often the case in studies using ex vivo human kidney stones. [Work supported by the National Space Biomedical Research Institute through NASA NCC 9-58 and NIH grants DK043881 and DK092197.]